(1) Field of the Invention
The invention relates to an assembly and method for holding and positioning a measurement instrument, and is directed more particularly to an assembly and method for holding and positioning a measurement probe close to a test body disposed for a fluid tunnel test, such as a wind tunnel test, or the like.
(2) Description of the Prior Art
It is known to determine hydrodynamic performance of a marine body, such as a vehicle hull, a torpedo, a mine, submersibles, and the like, by making a series of anemometry and pressure measurements around the test body in a controlled wind stream. The results are scaled, through a "Reynolds Number" correlation, to performance in the water. Inasmuch as an air tunnel generally requires less space and maintenance than a water-filled test tank, the use of air tunnels for determining hydrodynamic performance of marine bodies is attractive.
The cross-sectional geometry of many underwater vehicles is circular. Also, the cross section of many windtunnel wind delivery outlets is circular. Thus, there often is required a circle of measurement probes around the test body, usually mounted on arms extending into the test tunnel wind stream to map out the flow behaviors around the portions of the body under study. It is further required to produce such "maps" along the axial length of the test body portion under study.
Inasmuch as each measurement probe interferes with the air flow near the test body, the larger the number of probes used to acquire a complete picture, the more interference with normal flow is experienced. Thus, in an effort to obtain a more complete picture, one may, by overuse of probes, actually decrease the accuracy of the picture.
There is, therefore, a need for a system and method for mounting a modest number of probes which are readily and easily movable along the axis of the test body and radially and circumferentially of the test body, such that the modest number of probes provide the information heretofore obtained from a large number of probes, but without significant interference with fluid flow around the test body.